Calories to Macros Calculator
Convert any calorie number into protein, carbohydrate and fat grams — pick a split and see the exact conversion, worked out with the Atwater 4/4/9 factors.
Calculate Your Macros
Enter your daily calorie target. Typical ranges: 1,200–2,000 kcal (weight loss), 2,000–3,000 kcal (maintenance), 3,000–5,000+ kcal (athletic or bulking).
Range: 15–100 years. Adult macro ratios aren’t validated for under-19s — add your age and we’ll flag if these targets need a paediatrician’s sign-off.
Moderate exercise most days of the week. Recommended protein: 1.2–1.6 g/kg body weight (ISSN guidelines).
*This calculator is for informational purposes only. Please consult a healthcare professional before making any health decisions. See our medical disclaimer for more information.
Calculations are powered by the Atwater General Factor System, the universally accepted standard for macronutrient caloric conversion (protein: 4 kcal/g, carbohydrate: 4 kcal/g, fat: 9 kcal/g).
Quick Answer
How Do You Turn Calories Into Macros?
The conversion is one identity: grams = (calories × macro%) ÷ calories per gram. Protein and carbohydrate carry 4 calories per gram, so you divide their calories by 4; fat carries 9, so you divide by 9. Enter a calorie number and pick a split above, and the calculator runs all three divisions for you.
How Calories Convert to Grams
Every macro conversion comes back to a single rule: grams equal calories multiplied by the macro’s share of the day, then divided by the energy that macro carries per gram. Those energy densities are fixed — protein at 4 calories per gram, carbohydrate at 4, and fat at 9. That is the whole conversion, and it is the reason a percentage split and a calorie total together are enough to produce exact gram targets. You never need anything beyond your calorie number, the three percentages, and the 4/4/9 factors — which makes this the definitional step behind every other macro tool on the site.
A Full Worked Conversion
Take 2,200 calories on a balanced 30/40/30 split, step by step. Protein is 30% of 2,200, which is 660 calories, and dividing by 4 gives 165 grams. Carbohydrate is 40%, or 880 calories, again divided by 4 — that is 220 grams. Fat is the remaining 30%, another 660 calories, but divided by 9 because of its higher energy density, which comes to about 73 grams. So 2,200 calories on this split is 165 g protein, 220 g carbohydrate and 73 g fat. Enter your own total above and pick a split with the Macro Calculator to see it worked for your number; set the total itself with the Calorie Deficit Calculator.
Going the Other Way
The conversion runs backwards just as cleanly. To turn grams into calories, multiply the protein grams by 4, the carbohydrate grams by 4 and the fat grams by 9, then add the three results together — that sum is the calorie total those macros carry. It is the exact inverse of the division above, which is why the numbers always reconcile: split a total into grams, multiply the grams back, and you return to the total you started from. To size protein against your body weight rather than a flat percentage, use the Protein Intake Calculator. These figures are general estimates for healthy adults, not medical advice.
Gram targets use the Atwater general factor system — protein and carbohydrate at 4 calories per gram, fat at 9 — the same standard published in the Dietary Reference Intakes for Macronutrients (National Academies of Sciences, 2005). The split is arithmetic, not a personalised prescription; individual needs vary, so check with a clinician or registered dietitian before making changes if you manage a medical condition.
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